Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session E52: Physics of Batteries IIndustry
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Sponsoring Units: GERA FIAP Room: Hilton Baltimore Holiday Ballroom 3 |
Tuesday, March 15, 2016 8:00AM - 8:12AM |
E52.00001: Diffusion and possible freezing phases of Li-ions in LiFePO$_{\mathrm{4}}$ Yuen Yiu, Rasmus Toft-Petersen, Georg Ehlers, David Vaknin Elastic and inelastic neutron scattering studies of LiFePO$_{\mathrm{4}}$ single crystal reveal new Li-ion diffusion properties relevant to its function as Li-battery materials. In the past decade there has been broad interest in LiFePO$_{\mathrm{4}}$ and its related compounds, largely due to the applications of these materials as cathodes in Li- batteries. This is owing to these materials' high charge-discharge ability and conductivity, both of which are by virtue of the Li-ions' high mobility. In this talk, we present our findings on the temperature and directional dependence of Li-ions' diffusion in LiFePO$_{\mathrm{4}}$. LiFePO$_{\mathrm{4}}$ adopts the olivine structure at room temperature (Space group: \textit{Pnma}), which contains channels along principal crystalline directions that allow Li-ion motion. Elastic neutron scattering reveals lowering of symmetry from the Pnma structure below room temperature, which can be interpreted as the freezing of Li-ions, and can be subsequently linked to the reported decrease in Li-ion conductivity. Inelastic neutron scattering, in the 35K to 720K temperature range, shows temperature dependence, as well as anisotropy (i.e. along 0K0 versus 00L) of Li-ion diffusion. [Preview Abstract] |
Tuesday, March 15, 2016 8:12AM - 8:24AM |
E52.00002: Structural Properties and Electrochemical Performance of ZnO Nanosheets Grown Directly on Al substrate by Chemical Bath Deposition Techniques Ahmed Al-Asadi, Roberto Ferrera, Luke Henley, Nestor Lopez, Victor Carozo, Zhong Lin, Mauricio Terrones, Saikat Talapatra We will report on the synthesis {\&} electrochemical characterization of 2-dimentional zinc oxide grown directly on Al substrate by a simple chemical bath deposition method at low temperature (below 100$^{\mathrm{0}}$C). Detail structural characterizations of the synthesized ZnO sheets will be presented and discussed. The electrochemical performances of electrochemical double layer capacitors (EDLC) on electrodes fabricated using these materials were evaluated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy using various electrolytes. We found that high specific capacitance values (greater than 300 F/g) could be achieved using an aqueous electrolyte. The aforementioned results indicates the possibly for using 2-D ZnO architectures fabricated by this simple and cost efficient technique for future electrochemical energy storage devices. [Preview Abstract] |
Tuesday, March 15, 2016 8:24AM - 8:36AM |
E52.00003: In situ analysis of capacity fade in thin-film anodes for high performance Li-ion all-solid-state batteries Marina S. Leite, Chen Gong, Dmitry Ruzmetov, A. Alec Talin There is still a pressing need to understand how the solid-interfaces in Li-ion all-solid-batteries form, including their chemical composition and electrical characteristics. In order to resolve the origin of the degradation mechanism in Al anodes, we combine in situ scanning electron microscopy in ultra-high vacuum with electrochemical cycling, in addition to ex situ characterization of the morphological, chemical, and electrical changes of the Al anodes upon lithiation. An AlLi alloy capped by a stable Al-Li-O is formed on the top surface of the anode, trapping Li, which results in the capacity fade, from 48.0 to 41.5 $\mu $.Ah/cm$^{2}$ in two cycles [1]. The addition of a Cu capping layer is insufficient to prevent the device degradation because of the fast Li diffusion within Al. Yet, Si present extremely stable cycling: \textgreater 92{\%} of capacity retention after 100 cycles, with average Coulombic efficiency of 98{\%} [2]. Our in situ measurements represent a new platform for probing the real-time degradation of electrodes in all-solid-state batteries for energy storage devices. [1] M.S. Leite et al., J. Mater. Chem. A, \textbf{2}, 20552 (2014). i-Cover. [2] C. Gong et al., ACS Appl. Mater. Interfaces, 2015. DOI: 10.1021/acsami.5b07058 [Preview Abstract] |
Tuesday, March 15, 2016 8:36AM - 8:48AM |
E52.00004: Non-Destructive Measurement of $\textit{in-operando}$ Lithium Concentration in Batteries via X-Ray Compton Scattering Hasnain Hafiz, K. Suzuki, B. Barbiellini, Y. Orikasa, S. Kaprzyk, M. Itou, K. Yamamoto, Y. J. Wang, Y. Uchimoto, A. Bansil, Y. Sakurai, H. Sakurai Non-destructive determination of lithium distribution in a working battery is key for addressing both efficiency and safety issues. Although various techniques have been developed to map the lithium distribution in electrodes, these methods are mostly applicable to test cells. Here we propose the use of high-energy x-ray Compton scattering spectroscopy to measure the local lithium concentration in closed electrochemical cells. A combination of experimental measurements and parallel first-principles computations is used to show that the shape parameter $\textit{S}$ of the Compton profile is linearly proportional to lithium concentration and thus provides a viable descriptor for this important quantity. The merits and applicability of our method are demonstrated with illustrative examples of $Li_{x}Mn_{2}O_{4}$ cathodes and a working commercial lithium coin battery CR2032. [Preview Abstract] |
Tuesday, March 15, 2016 8:48AM - 9:00AM |
E52.00005: In-Situ AFM Investigation of Solid Electrolyte Interphase Formation and Failure Mechanisms in Lithium --Ion Batteries. Thomas Mueller, Ravi Kumar, Anton Tokranov, Teddy Huang, Chunzeng Li, Xingcheng Xiao, Brian Sheldon The formation and evolution of the solid electrolyte interphase (SEI) is critical for lifetime and performance of lithium-ion batteries (LIBs), particularly for LIBs with high energy density materials such as silicon. Si has almost ten time theoretical specific capacity vs graphite, but its volume changes during cycling (up to 400{\%}) put enormous strains on the SEI layer, resulting in continuous capacity loss. In this study we report in situ atomic force microscopy (AFM) investigation on the formation and failure mechanisms of SEI layer using patterned Si island structures. Due to the shear lag effect, patterned Si islands go through lateral expansion and contraction, putting the SEI layer in tension and compression during lithiation and delithiation, respectively. Experimentally, we performed the studies in a glovebox with \textless 1 ppm O2 and H2O, using PeakForce Tapping to image the extremely fragile SEI layer. We show for the first time the in operando cracking of SEI layer. To understand the mechanics of the SEI layer, the critical strain for cracking was derived from a progression of the AFM images. Our studies provide new insight into SEI formation, evolution and its mechanical response, and offer guidance to tailor passivation layers for optimal performance. [Preview Abstract] |
Tuesday, March 15, 2016 9:00AM - 9:12AM |
E52.00006: Why LiFePO$_{4}$ is a safe battery electrode: Coulomb repulsion induced electron-state reshuffling upon lithiation Yung Jui Wang, Xiaosong Liu, B. Barbiellini, Hasnain Hafiz, Susmita Basak, Jun Liu, Thomas Richardson, Guojiun Shu, Fangcheng Chou, Tsu-Chien Weng, Dennis Nordlund, Dimosthenis Sokaras, B. Moritz, T. P. Devereaux, Ruimin Qiao, Yi-De Chuang, Arun Bansil, Zahid Hussain, Wanli Yang We performed systematic experimental and theoretical studies based on soft X-ray emission, absorption, and hard X-ray Raman spectroscopy of Li$_{x}$FePO$_{4}$. The results show a non-rigid electron-state reconfiguration of both the occupied and unoccupied Fe-3d and O-2p states during the (de)lithiation process. The critical 3d electron state configurations are consistent with the calculations based on MBJGGA+U framework, which improves the overall lineshape prediction compared with the conventionally used GGA+U method. The combined experimental and theoretical studies show that the non-rigid electron state reshuffling guarantees the stability of oxygen during the redox reaction throughout the charge and discharge process of LiFePO$_{4}$ electrodes, leading to the intrinsic safe performance of the electrodes. Work supported by the US DOE. [Preview Abstract] |
Tuesday, March 15, 2016 9:12AM - 9:24AM |
E52.00007: An experimental and computational investigation of structural dependence of catalytic properties of Pt-Ru nanoparticles Binay Prasai An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail is described and exemplified on Pt--Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models are built by molecular dynamics simulations and further refined against the experimental PDF data by reverse Monte Carlo simulations and analyzed in terms of structural characteristics. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt--Pt and Ru--Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the observed enhancement of the catalytic activity of PtxRu100$-$x alloy NPs at x $\sim $ 50. [Preview Abstract] |
Tuesday, March 15, 2016 9:24AM - 9:36AM |
E52.00008: Detailed characterization of lithium diffusion mechanisms in crystalline silicon using the kinetic Activation-Relaxation Technique. Mickaƫl Trochet, oscar Antonio Restrepo Gutierrez, normand Mousseau Silicon displays a potential for high-capacity anode material for lithium-ion batteries as it can absorb large quantities of this metal. Yet, very little is understood about the evolution of diffusion mechanisms and migration barriers as the concentration of lithium increases. Until now, for example, simulations studies were limited by the time scale over which diffusion takes place. Here, we use the kinetic activation relaxation technique (kART[1]), an unbiased off-lattice Monte Carlo method with on-the fly catalog building, coupled with the ReaxFF forcefield to follow diffusion of Li in $c-$Si over timescale of seconds and more at room temperature, obtaining detailed information about the whole set of possible diffusion mechanisms as the local environment evolves. We first present a detailed characterization of Li diffusion in the presence of 1 to 3 impurities and then show the evolution of systems with a higher concentration of solute as Li aggregate. These results provide a first detailed picture of the onset of Li aggregating into this high-capacity material, as it modifies the structure through local rearrangements and long-range elastic deformations, crucial information for the development of the next generation of high-capacity anode. $\backslash $pard$\backslash $pard[1] M. Trochet \textit{et al}, ``Diffusion of point defects in crystalline silicon using the kinetic activation-relaxation technique method,'' \textit{Phys. Rev. B}, vol. 91, no. 22, p. 224106, 2015. [Preview Abstract] |
Tuesday, March 15, 2016 9:36AM - 9:48AM |
E52.00009: Gold Nanoparticles-Enhanced Proton Exchange Membrane (PEM) Fuel Cell Hongfei Li, Cheng Pan, Ping Liu, Yimei Zhu, Radoslav Adzic, Miriam Rafailovich Proton exchange membrane fuel cells have drawn great attention and been taken as a promising alternated energy source. One of the reasons hamper the wider application of PEM fuel cell is the catalytic poison effect from the impurity of the gas flow. Haruta has predicted that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate to be the perfect catalysts of the CO oxidization, yet the synthesis method is difficult to apply in the Fuel Cell. In our approach, thiol-functionalized gold nanoparticles were synthesized through two-phase method developed by Brust \textit{et al}. We deposit these Au particles with stepped surface directly onto the Nafion membrane in the PEM fuel cell by Langmuir--Blodgett method, resulting in over 50{\%} enhancement of the efficiency of the fuel cell. DFT calculations were conducted to understand the theory of this kind of enhancement. The results indicated that only when the particles were in direct surface contact with the membrane, where AuNPs attached at the end of the Nafion side chains, it could reduce the energy barrier for the CO oxidation that could happen at T\textless 300K. [Preview Abstract] |
Tuesday, March 15, 2016 9:48AM - 10:00AM |
E52.00010: One pot electrochemical synthesis of polymer/CNT/metal nanoparticles for fuel cell applications. Lakshman Ventrapragada, Jingyi Zhu, Mehmet Karakaya, Ramakrishna Podila, Apparao Rao Carbon nanotubes (CNTs) have become a key player in the design of materials for energy applications. They gained their popularity in industrial and scientific research due to their unique properties like excellent conductivity, high surface area, etc. Here we used chemical vapor deposition (CVD) to synthesize two types of CNTs namely, helically coiled CNTs and vertically aligned CNTs. These CNTs were subsequently used to make composites with conducting polymers and metal nanoparticles. One pot electrochemical synthesis was designed to electropolymerize aniline, pyrrole etc. on the surface of the electrode with simultaneous deposition of platinum and gold metal nanoparticles, and CNTs in the polymer matrix. The as synthesized composite materials were characterized with scanning electron microscope for surface morphology and spectroscopic techniques like Raman, UV-Vis for functionality. These were used to study electrocatalytic oxidation of methanol and ethanol for alkaline fuel cell applications. Electrodes fabricated from these composites not only showed good kinetics but also exhibited excellent stability. Uniqueness of this composite lies in its simple two step synthesis and it doesn't involve any surfactants unlike conventional chemical synthesis routes. [Preview Abstract] |
Tuesday, March 15, 2016 10:00AM - 10:12AM |
E52.00011: Energy storage mechanism for hybrid battery Jun Feng, Natasha Chernova, Fredrick Omenya, Alok Rastogi, Stanley Whittingham Many devices require both high energy and high power density, and lithium ion batteries and super-capacitors cannot separately always meet the requirements. In this work, we study the operating mechanism of a hybrid battery, which combines the best properties of batteries and supercapacitors. We analyze the lithium ion storage mechanism using XRD, Raman, TEM and electrochemical measurements. The model system studied combines a non-intercalating carbon black anode with a LiFePO$_{\mathrm{4}}$ cathode. At 50{\%} state of charge, XRD data for LiFePO$_{\mathrm{4}}$ cathode material shows a mixture of LiFePO$_{\mathrm{4}}$ and FePO$_{\mathrm{4}}$, indicating battery reaction. On the other hand, the activated carbon remains structurally unchanged. We also discuss the impact of a range of activated carbon/ LiFePO$_{\mathrm{4}}$ (AC/LFP) ratios. From cyclic voltammetry and charge/discharge results, the system exhibits battery-domain characteristics when the AC/ LFP ratio is below one, but showing more supercapacitor-domain traits when the ratio is higher. Besides, the systems have higher rate capacity at AC/LFP ratio around four as compared to one. This research is supported by NSF under Award Number 1318202. [Preview Abstract] |
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